DE102012218140A1 - Calibration element e.g. diaphragm for use in wet calibration device of extrusion apparatus for extruding plastic profile for window, has mechanical scraper which is arranged in extrusion direction of plastic profile - Google Patents

Abstract

The calibration elements (10,11) comprise nozzles which are provided for directing flow of cooling water against extrusion direction (E) of plastic profile (2). The rollers are arranged at the upper and lower edges of opening (20) in vacuum tank (1). A mechanical scraper is arranged in the extrusion direction of plastic profile. An independent claim is included for method for the calibration of a plastic profile.

Description

The invention relates to a calibration element having the features of claim 1 and a calibration method having the features of claim 10.

Plastic profiles made of thermoplastic materials are manufactured by extrusion. In this case, a nozzle and a calibration are used for the shaping of a plastic profile.

Calibrations for the production of plastic profiles, e.g. Window profiles, usually have a dry and a wet calibration device, the hot extrudate after exiting the nozzle first passes through the Trockenkalibrierungs- and then the Naßkalibrierungsvorrichtung. At the end of the calibration and after complete cooling of the plastic profile to room temperature, the plastic profile must have the desired contour.

The wet calibration device has a plurality of vacuum tanks arranged one behind the other for substantially cooling the plastic profile, after it has already been partially cooled in the dry calibration. In the wet calibration device, approximately 500 mm calibration elements (so-called short calibrators or diaphragms) are arranged at intervals of approximately 100 mm at the outset, each having a passage opening which largely corresponds to the geometry of the plastic profile.

The vacuum tanks are basically closed on all sides, and have openings for the entry and exit of the plastic profile only at the end faces. The vacuum tanks are subjected to negative pressure in the order of about 30 to 200 mbar, whereby the plastic profile is slightly "inflated" and applies to the through holes of the calibration.

The plastic profile thus cools in a defined shape, so that the shape retention is ensured. The cooling water flows through the vacuum tanks from a few supply lines to a few outlets. The vacuum in the vacuum tanks only has to be applied via a vacuum connection and then acts in all vacuum tank interiors.

The production costs for the calibration elements are comparatively low because they do not require supply and distribution holes for underpressure and cooling water.

The wet calibration device upstream of the dry calibration device has up to eight calibration elements. These calibration elements each have running surfaces which correspond approximately to the contour of the plastic profile. However, there are in detail dimensional or geometric differences to follow the length reduction with decreasing temperature of the plastic and to compensate for the delay due to different cooling rates.

The dry calibration devices are supplied with negative pressure and with cooling water. The negative pressure applied to the running surfaces of the calibration elements causes the plastic profile to be sucked onto the running surfaces. The negative pressure acts e.g. via so-called vacuum slots between the plastic profile and the calibration and ensures that the plastic profile rests without play on the tread, so that the plastic profile occupies a defined outer contour. Via connection and distribution bores, a flow connection to vacuum pumps is established within the calibration device. Outside the dry calibration devices, the vacuum is transmitted by means of hoses and connection points.

Due to the close contact of the plastic profile with the running surfaces for Trockenkalibrierungsvorrichtung takes place a heat transfer from the hot plastic profile to the cold Trockenkalibrierungsvorrichtung.

In order to prevent or at least minimize an increase in the temperature of the dry calibration devices, they are cooled, usually continuously. This is done by passing cooling water through cooling channels close to the tread. Each of these cooling channels requires a supply line and a discharge for the cooling water, but several cooling channels can be combined. Thus, two water connections are required for each cooling circuit, each for the supply line and for the discharge.

The cooling water is normally used in a refrigeration cycle, i. it absorbs heat in the area of the calibration and this is withdrawn by a cooling device.

The cooling water treatment (cooling unit, circulating pumps, cooling water central tank, filter systems, etc.) is summarized in one area of the extrusion plant, where there is usually a spatial separation between the cooling water treatment and the cooling water consumers (extrusion lines with calibration).

The cooling water supply includes closed or open connection pipes (pipelines and / or channel-like channels). In a storage tank is a larger Cooling water stored. This storage tank is designed to supply multiple extrusion lines and, depending on production requirements, only a few or all extrusion lines can produce at the same time.

The storage capacity is usually about 10 to 200 m ^3, depending on the number of extrusion lines to be supplied. In the sense of economical use of the cooling water, this is usually used for one to three months. Open cooling water circuits (water has contact with air, channel flow) are very common.

Experience has shown that the cooling water is often contaminated by organic and / or inorganic contaminants (e.g., particles) due to the relatively long duration of use in the extrusion line. This is recognizable because the cooling water is usually slightly to very cloudy.

Especially in the field of vacuum tanks, the plastic profile has direct contact with the cooling water. Particles from the cooling water, e.g. Sand or lime particles can accumulate on the sensitive running surfaces of the calibration elements or on their leading edge, which then causes scratches on the plastic profile surface. Disturbing such scratches are mainly on the visible surfaces of plastic profiles. These are those surfaces of the plastic profiles, e.g. in the fully installed window are oriented inward in the room or outward to the outside.

The filter systems used for the cooling water are usually not sufficient to reliably avoid such scratches, because hardly all particles can be filtered out.

It is therefore an object to provide an apparatus and a method which minimizes these problems.

This object is achieved by a device having the features of claim 1.

By using a mechanical and / or fluid mechanical means for removing and / or keeping away particles from a surface of the plastic profile, mechanical damage to the surface is avoided.

In this case, the various mechanical and / or fluidic means for removing and / or keeping particles away from a surface of the plastic profile can be designed in particular as an additional device to conventional diaphragms for shaping plastic profiles, which are used in a vacuum tank for calibration. This can be prevented that, e.g. particles floating in the cooling water (for example dirt) can be fixedly attached to running surfaces of the calibration elements, so that the particles can not leave scratches on the sensitive plastic profile surface.

It is advantageous if a nozzle device is used for the targeted flow of a surface of the plastic profile, wherein the flow has only directional components that point away from the calibration or parallel to him. It is particularly advantageous if the nozzle device can be flowed through by a cooling water flow (K) directed essentially against the extrusion direction, since in this way the already existing cooling water flow can be used to keep particles away from the calibration element.

Due to the flow of a surface of the plastic profile with cooling water, in particular along the visible surface of the plastic profile particles deposited on the visible surface are stirred up before contact with the running surface of the diaphragm and / or rinsed away.

Additionally or alternatively, it is advantageous if at least one movable guide element is provided for a surface of the plastic profile, in particular for automatic unrolling on the surface. It is particularly advantageous if the at least one movable guide element is designed as a roller, in particular with a convex outer contour. In this case, the immersion depth of the at least one movable guide element relative to the plastic profile can be made adjustable.

Additionally or alternatively, the calibration element has a mechanical wiper for a surface of the plastic profile. It is advantageous if the at least one mechanical wiper has a soft elastic element for contacting the surface of the plastic profile.

The object is also achieved by a mechanical and / or fluid mechanical means for removing and / or keeping particles away from a surface of the plastic profile to prevent mechanical damage to the surface, particularly for use with a calibration element according to at least one of claims 1 to 8 is designed and furnished.

Furthermore, the object is also achieved by a method having the features of claim 10.

Embodiments of the invention will be explained with reference to figures. Showing:

1 a perspective sectional view of a vacuum tank of a wet calibration;

2 a sectional view through the vacuum tank according to 1 with a plastic profile;

3 a detailed sectional view of a vacuum tank with a first embodiment of a calibration device with a fluidic means for keeping away and / or removing particles;

3A a schematic representation of a flow in an embodiment according to 3 ;

4 a perspective view of the first embodiment of a calibration device;

5 a front view of the first embodiment of a calibration device according to 4 ;

6 a sectional view through the first embodiment of the calibration according to 4 and 5 ;

7 a perspective view of the second embodiment of a calibration device with a mechanical means in the form of a spherical roller for keeping away and / or removing particles;

8th a front view of the second embodiment of a calibration according to 7 ;

9 a sectional view through the second embodiment of the calibration according to 7 and 8th ;

10 a perspective view of the third embodiment of a calibration device with a mechanical means in the form of a scraper for holding and / or removing particles;

11 a sectional view through the third embodiment of the calibration according to 11 ,

The present invention relates to calibration elements 10 . 11 (Apertures) and / or measures on the running surfaces of these calibration elements 10 . 11 , whereby despite the presence of interfering impurities in the cooling water scratches on the plastic profiles 2 (please refer 2 ) are largely avoided. The objective is to jam or deposit particles 3 (especially hard particles) (see 3 ) on running surfaces 4 the calibration elements 10 . 11 to avoid.

In this case, embodiments are described by way of example, which individually can be used individually or together in combination.

Washing away particles

In the embodiment according to 1 The wet calibration device has a plurality of vacuum tanks arranged one behind the other 1 on. In the vacuum tanks 1 are consecutively several calibration elements 10 . 11 arranged on the outer surfaces facing the walls of the vacuum tank 1 largely seal off. Each calibration element 10 . 11 has an opening inside 20 . 21 for the in 1 not shown plastic profile 2 on. The openings 20 . 21 correlate with the outer contour of the plastic profile 2 ,

In 1 the extrusion direction E is provided from right to left.

The cooling water flow is here opposite to the extrusion direction E, ie from left to right. The cooling water K _a is introduced into the leftmost chamber, flows through not shown here holes or openings in the calibration 10 . 11 through and passes through all chambers to the extreme right chamber. This right chamber, the cooling water K _from (and possibly present air) is sucked again.

In 2 is a longitudinal section through the vacuum tank 1 according to 1 with a plastic profile 2 shown. In the left chamber, the supply port for the cooling water K _is shown, illustrating the suction opening for the exiting cooling water _and infiltrated air K in the right ventricle.

The cooling water supply K _a is controlled by means of a tap or by the flow resistance in the supply line so that largely independent of the negative pressure in the vacuum tank, a certain throughput, for example in the range of 0.2 to 1 m ³ / h per 1 m tank length occurs.

At the suction opening on the right, a negative pressure in the range of about 0.05 to 0.2 bar is applied, which decreases from chamber to chamber to the left to the cooling water supply.

The pressure difference between adjacent chambers results from the cooling water flow rate and the flow resistance in the apertures of the aperture.

The transported air additionally has a small influence. The negative pressure or alternatively the supplied amount of cooling water are adjusted so that there is no pressure in any chamber, because this would indeed "squeeze" the plastic profile and warping flat surfaces in an inadmissible manner inward, which fundamentally contradicts the purpose of the calibration.

In 3 is a chamber of the vacuum tank 1 shown. This is through the four walls of the vacuum tank 1 and left and right by a calibration element 10 . 11 educated. The plastic profile 2 moves in this representation from right to left in the extrusion direction.

A water flow can eg against the extrusion direction E of the plastic profile 2 be directed so that the particles 3 from the inlet to the calibration element 10 . 11 be washed away. In alternative embodiments, the flow is oriented so that the targeted flow 5 the surface of the plastic profile 2 has only directional components, that of the calibration element 10 show away (see 3A ). For example, a cross flow before the entry of the plastic profile 2 into the calibration element 10 . 11 used to particle 3 wash away. In 3 is the flow 5 sloping down onto the plastic profile 5 directed, so that no directional component is present on the calibration 10 shows. In 3A is an enlarged view of the opening 20 of the calibration element 10 shown. Before the opening 20 the particles collect 3 at. It will - depending on the orientation of the nozzle device 30 - Different directions of flow 5 the cooling water shown schematically. The flow directions 5 are all in a vertical plane and have no directional components, which in the direction of the calibration 10 demonstrate. The cooling water hits in this case obliquely from above at different angles on the plastic profile 2 on. In an analogous manner, the flow 5 be formed in the horizontal direction, so that particles can be washed away transversely to the extrusion direction E (or horizontally).

In the calibration elements 10 . 11 are nozzle devices 30 . 31 arranged for the cooling water. The nozzle devices 30 . 31 are designed here as inclined slots or as oblique holes (see 4 . 5 and 6 ), so that the outflowing cooling water 5 only has directional components that are not on the opening 20 . 21 in the calibration element 10 point. In principle, the nozzle cross-sections may have any desired shape, which may in particular be designed so that they are at critical points of the surface of the plastic profile 2 generates a particularly strong flow.

Due to the negative pressure applied in an upstream chamber, there is a pressure gradient in the chambers: the absolute pressure P in the chambers decreases from left to right (ie counter to the extrusion direction), P ₁ <P ₂ <P ₃ . The cooling water is thus through the oblique nozzles 30 . 31 sucked and flows from left to right. For comparatively small pressure differences between two adjacent chambers are already sufficient, for example in the range of 0.01 to 0.05 bar.

In 4 and 5 are the nozzle devices 30 . 31 for generating the targeted flow 5 shown in more detail.

4 represents a frontal view of a calibration element 10 at which above and below the opening 20 for the plastic profile 2 (not shown here) nozzles 30 . 31 are arranged. The extrusion direction E points vertically into the plane of the paper, the cooling water K flows out substantially perpendicularly out of the plane of the paper. Through the nozzles 30 . 31 the cooling water is applied to the plastic profile 2 steered and impinges obliquely on the plastic profile surface.

In 6 becomes the plastic profile 2 from right to left through the calibration element 10 moved and is due to the air pressure from the inside out to the tread 4 of the calibration element 10 pressed. Have particles on the plastic profile surface during the passage of the chamber off or attached, so these are not in the gap between the plastic profile 2 and running surface of the calibration element 10 retracted, but due to the outflowing cooling water 5 in the vicinity of the tread 4 whirled up and / or washed away. Hard impurities can not adhere to the tread 4 of the calibration element 10 . 11 or in the region of the rounded edge on the inlet side of these running surfaces 4 set and subsequently cause no disturbing scratches on the plastic profile surface.

In an analysis of the frequency of annoying scratches on plastic profiles 2 It was found that the scratches increased on top surfaces of plastic profiles 2 occur, based on the position of the plastic profile 2 during the extrusion. This suggests that contamination of the water in the vacuum tank 1 also on the plastic profile 2 settle and therefore increasingly accumulate on horizontal surfaces. Once such a settled particle 3 with the plastic profile 2 mitwandert, succeeded to a calibration element 10 . 11 , Very large particles, eg sheared crumbs of PVC plastic profile from the startup process with dimensions of about 0.5 mm or larger, are from the end face of the calibration 10 . 11 stripped and then can not cause scratches. Smaller particles with dimensions below about 1.0 mm may be in the area of the rounded inlet edge of the calibration element 10 . 11 wedging or they will be in the narrow gap between the plastic profile and the calibration element 10 . 11 retracted and store due to small irregularities on the tread of the calibration 10 . 11 at.

In both cases, the plastic profile surface slides along these contaminants, resulting in scratches. The harder this particle 3 is (sand, lime or similar contamination of the water), the longer, both temporally and spatially related to the run length of the plastic profile, a scratch is caused - until the particle 3 in turn, has been abraded as a result of wear.

Movable guide element

Alternatively or additionally, scratches can be avoided when the particles are 3 not on a stationary tread 4 of the calibration element 10 . 11 can attach. This can eg by a movable guide element 40 done that, a stationary tread 4 replaced by a movable tread, in particular a rotating tread.

This is in the 7 to 9 shown. 7 shows in a perspective view a calibration element 10 , In the illustrated embodiment, the movable guide element 40 designed as a roller, each at the top and bottom of the opening 20 for the plastic profile 2 is arranged (see 8th ). The roles 40 are designed as freely rotatable rollers, by the moving plastic profile 2 is moved.

Get particles 3 or other contaminants in the narrow gap between the plastic profile surface and the rotatable roller 40 , these are transported further and will usually continue to remain as suspended particles in the water. These particles 3 leave less or no scratches on the plastic profile 2 but either cause no marking at all or maybe just a small imprint, which hardly touches the surface of the plastic profile 2 impaired.

7 to 9 show a calibration element 10 with two roller inserts 40 , which the visible surfaces of the relevant plastic profile 2 (not shown here) are assigned. These roller inserts 40 are mounted with a pin in a guide slot and are rotatable with little force application. The plastic profile 2 is with a vacuum in the vacuum tank 1 proportional force against this role 40 pressed. The role 40 is not cylindrically shaped, but has a convex contour in longitudinal section, so that the plastic profile 2 similar to the normal calibration element 10 is arched inside. The position of the roll 40 in the axial direction (here horizontal) is by a respective stop collar opposite the opening 20 of the calibration element 10 . 11 certainly. The position with respect to the distance to the plastic profile 2 (here vertical) is determined by the depth of the guide slot. Alternatively, the depth can also be limited by a screw. This has the great advantage that the height of the plastic profile 2 and or the flatness of the plastic profile 2 is adjustable by appropriate adjustment of the screws, which can be done very easily during the current extrusion operation. It was found that hard dirt particles from the water are not attached to the rollers 40 attach. Will a dirt particle in the gap between roller 40 and plastic profile 2 retracted, this is usually only further promoted and then remains back as pollution floated in the cooling water. As a result, there is hardly any risk of scratching on the sensitive plastic profile surface.

Mechanical scraper

Furthermore, alternatively or additionally, a mechanical scraper 50 be used. Embodiments thereof are in 10 to 11 shown. In 10 is a mechanical scraper in a perspective view 50 shown in the direction of extrusion E before the calibration 10 is arranged.

The mechanical wiper 50 , similar to a windscreen wiper rubber, the particles can 3 from an entry into the calibration element 10 . 11 hold.

Has a particle 3 deposited on the plastic profile surface and reaches this scraper 50 so it will be stopped or if the scraper 50 is arranged obliquely to the extrusion direction E, laterally derived. Even if there is a particle 3 on the scraper 50 attaches, this causes no scratch, because of the soft elastic scraper 50 can not selectively exert a large force, which is a prerequisite for a scratch.

In 10 to 11 is the calibration element 10 . 11 shown, which with scrapers 50 whose function is comparable to a windshield wiper. The squeegee is made of a soft elastic plastic, such as foam rubber, this is easily by means of metal bracket to the visible surface of the plastic profile to be calibrated 2 pressed. The wiper surface takes the contour of the plastic profile 2 and therefore strips off the continuous plastic profile surface. Have particles on this plastic profile surface 3 deposited, these are retained or stripped. These particles 3 can also be deposited in the pores of the squeegee. Since the squeegee in turn can not exert a large pressing force on such dirt particles, the dirt particles can not be pressed firmly against the plastic profile surface and therefore can not leave scratches on this. The squeegee can be directly in front of the end face of the calibration 10 . 11 be arranged or with a short distance in front, as well as transversely to the extrusion direction of the plastic profile 2 or at an oblique angle to this. Such scrapers 50 can also in combination with the obliquely directed against the plastic profile surface flow openings 30 . 31 for the cooling water and / or with the roller inserts 40 be used.

LIST OF REFERENCE NUMBERS

1

vacuum tank

2

Plastic profile

3

particle

4

Tread in calibration element

5

targeted flow onto the plastic profile

10, 11

Calibration element (aperture) in vacuum tank

20, 21

Opening in calibration element for the plastic profile

30, 31

Nozzle for cooling water in calibration element

40

 movable guide element for the plastic profile

50

mechanical wiper

e

extrusion direction

K

Cooling water flow

K _a

 Cooling water influx

K _off

Kuhlwasserabfluss

Claims (10)

Calibration element in a wet calibration of an extrusion device for a plastic profile, characterized by a mechanical and / or fluid mechanical means ( 30 . 31 . 40 . 50 ) for the removal and / or removal of particles ( 3 ) from a surface of the plastic profile ( 2 ) to prevent mechanical damage to the surface. Calibration element according to claim 1, characterized by a nozzle device ( 30 . 31 ) for targeted flow ( 5 ) a surface of the plastic profile ( 3 ), whereby the flow ( 5 ) has only directional components that are separated from the calibration element ( 10 . 11 ) show away or lie parallel to it. Calibration element according to claim 2, characterized in that the nozzle device ( 30 . 31 ) by a substantially against the extrusion direction (E) directed cooling water flow (K) can be flowed through. Calibration element according to at least one of the preceding claims, characterized by at least one movable guide element ( 40 ) for a surface of the plastic profile ( 2 ), in particular for automatic unrolling on the surface. Calibration element according to claim 4, characterized in that the at least one movable guide element ( 40 ) is designed as a role, in particular with a convex outer contour. Calibration element according to claim 4 or 5, characterized in that the immersion depth of the at least one movable guide element ( 40 ) opposite the plastic profile ( 2 ) is adjustable. Calibration element according to at least one of the preceding claims, characterized by at least one mechanical scraper ( 50 ) for a surface of the plastic profile ( 2 ). Calibration element according to claim 7, characterized in that the at least one mechanical scraper ( 50 ) a soft elastic element for contacting the surface of the plastic profile ( 2 ) having. Mechanical and / or fluid mechanical means ( 30 . 31 . 40 . 50 ) for the removal and / or removal of particles ( 3 ) from a surface of the plastic profile ( 2 ) designed and arranged for preventing mechanical damage to the surface especially for use together with a calibration element according to at least one of claims 1 to 8. Method for calibrating a plastic profile, characterized in that during the extrusion of the plastic profile ( 2 ) Particles ( 3 ) by a mechanical and / or fluid mechanical means ( 30 . 31 . 40 . 50 ) from a surface of the plastic profile ( 2 ) and / or removed.

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